The Exposure Assessment Core provides exposure monitoring, analysis, and modeling services in support of the overall goals of the proposed Center and of the specific aims of the individual research projects. In addition, the Core will develop important new data on the distributions of indoor and outdoor concentrations of PM2.5, diesel exhaust particulates (DEP), NO2, and of indoor allergens in a large community of color in Northern Manhattan, an area with rates of asthma and adverse birth outcomes that are among the highest in the Nation. Specifically, the Core will develop estimates of prenatal and/or postnatal exposures to environmental pollutants for subjects enrolled in the Center's etiologic research studies. Based on personal sampling of pregnant mothers and indoor sampling of house dust, dustborne allergens (cockroach, mouse, dust mite) in a cohort of 400 pregnant women. PAH monitoring and analysis, funded under Dr. Perera's existing NIEHS grant, will include benzo[a]anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene, benzo[a]pyrene, chrysene/iso-chrysene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, and pyrene. For all 400 infants, the Core will monitor and/or model infant exposure between 12 and 18 months of age to dustborne allergens (cockroach, mouse, dust mite), PM2.5, of the remaining pollutants will be estimated in all 400 homes based on detailed measurements in a representative subset of 80 homes at 12 and 18 months, using a regression on home, occupant, and neighborhood characteristics. Information on neighborhood characteristics, including quality of house and proximity to major roadways and pollution point sources, will be developed using a geographic information system (GIS) for Northern Manhattan. The core will describe and analyze distributions of residential indoor and outdoor concentrations of PM2.5, DEP, NO2, and indoor allergens in a representative subset of 80 subjects, 40 each from Harlem and Washington Heights. Using these data, the Core will analyze the relationships of indoor and outdoor concentrations, of residential outdoor and central site monitors in each community, and the influence of seasonal changes on these measurements. In support of the allergen intervention study, the Core will re-measure indoor dust-borne allergen concentrations in 120 homes before (24 months postnatal) and after (30 and 36 months postnatal) a comprehensive indoor pest intervention. Finally, the Core will serve as a resource to Center Investigators in the design of future studies addressing childhood exposures to environmental toxicants in Northern Manhattan.